jQuery how to DRY the similar onclick event calls

I want to listen to two input change events, when one of the changes, check the checkbox and disable the element. Likewise, it needs to roll the checkbox back to the previous state when the value of input boxes back to the default values. The click function looks like 90% resemblance, how to DRY them?

var payment = 'old payment';        
var billAdr = 'old billAdr';

$('#payment').val(payment);
$('#bill-adr').val(billAdr);

$('#payment').on('input', function() {
  var newPayment = $('#payment').val();
  if(newPayment !== payment) {
    $("#save-nxt-time").attr('checked', true);
    $("#save-nxt-time").prop('disabled', true);
  } else {
    var newBillAdr = $('#bill-adr').val();
    if(newBillAdr === billAdr) {
      $("#save-nxt-time").prop('disabled', false);
      $("#save-nxt-time").attr('checked', false);
    }
  }
});

$('#bill-adr').on('input', function() {
  var newBillAdr = $('#bill-adr').val();
  if(newBillAdr !== billAdr) {
    $("#save-nxt-time").attr('checked', true);
    $("#save-nxt-time").prop('disabled', true);
  } else {
    var newPayment = $('#payment').val();
    if(newPayment === payment) {
      $("#save-nxt-time").prop('disabled', false);
      $("#save-nxt-time").attr('checked', false);
    }
  }
});

<!DOCTYPE html>
<html>
<head>
  <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script>
</head>
<body>
  <form action="/#">
    <label for="payment">payment</label>
    <input type="text" id="payment" name="payment">
    <br>
    <label for="bill-adr">bill address</label>
    <input type="text" id="bill-adr" name="bill-adr">
    <br>
    <input type="checkbox" id="save-nxt-time">
    <label for="save">Save to next time</label><br><br>
    <input type="submit" value="Submit">
  </form>
</body>
</html>

Solution

const oldPa = 'old payment';
const oldBi = 'old billAdr';

const $next = $('[name="save-nxt-time"]');
const $paym = $('[name="payment"]').val(oldPa);
const $bill = $('[name="bill-adr"]').val(oldBi);
const $paBi = $paym.add($bill);

$paBi.on('input', () => {
  const bool = $paym.val() !== oldPa || $bill.val() !== oldBi;
  $next.prop({disabled: bool, checked: bool});
});

form label {display: block;}

<form action="/#">
  <label><span>Payment</span> <input type="text" name="payment"></label>
  <label><span>Billing address</span> <input type="text" name="bill-adr"></label>
  <label><input type="checkbox" name="save-nxt-time"> <span>Save to next time</span></label>
  <input type="submit" value="Submit">
</form>

<script src="//ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script>